The director of Maryland's troubled health insurance exchange resigned Friday amid ongoing technical problems and questions about a Caribbean vacation she took while the online marketplace faltered.

Rebecca Pearce, hired two years ago to build a $107 million exchange, leaves her post as officials struggle to repair the system that launched Oct. 1.

The exchange's rocky start and low enrollment have become ammunition for political attacks on Lt. Gov. Anthony Brown, who was tasked by the governor with overseeing the state's implementation of the federal health care reform law.

The board of the Maryland Heath Benefit Exchange accepted Pearce's resignation during an emergency session Friday night. In a statement, Joshua Sharfstein, the state health secretary and board chairman, said Pearce "worked tirelessly and with tremendous dedication."

Pearce, whose starting salary in 2011 was $175,000, will be replaced on an interim basis by Carolyn Quattrocki, a top adviser to Gov. Martin O'Malley.

As state lawmakers grilled Sharfstein on Nov. 26 on why the health exchange was still broken, Pearce was on a week's vacation in the Cayman Islands.

During the trip, she could not be reached by phone, email or text, the health department said Friday.

Brown said in an interview Friday that he did not know Pearce planned to leave town until she was already gone. He called her absence during the week of Thanksgiving a "very" big problem. "We just launched a staff surge and we needed all hands on deck," he said. "Now is not the time to take a vacation."

Pearce did not return a call seeking comment on her resignation or her trip.

As of Friday, 3,758 people had enrolled in private insurance through the exchange. Maryland was one of 14 states that chose to build their own exchanges instead of relying on the federal government. State officials had hoped to enroll 150,000 by the end of March.

O'Malley said last week he wanted the exchange's major problems resolved by mid-December, leaving just one week for residents to sign up for insurance that will take effect Jan. 1.

As recently as Tuesday, Pearce appeared in charge of the exchange and repairing the technical problems such as frozen screens that have prevented people from signing up for policies. At a hearing in Annapolis, she said the state still hoped to reach its enrollment goals.

Behind the scenes, Brown and other officials said, much of Pearce's day-to-day control of the exchange had recently been handed to Information Technology Secretary Isabel FitzGerald.

While Pearce, as the head of a quasi-public institution, was not required to ask permission to take vacation, the lieutenant governor's political rivals in the race to succeed O'Malley faulted Brown for her absence.

"Lieutenant Governor Brown's poor leadership and mismanagement is deeply troubling to all of us who want to see Obamacare succeed," said Democrat Douglas F. Gansler's campaign spokesman, Bob Wheelock.

Republican Harford County Executive David Craig questioned the O'Malley-Brown administration's commitment to resolving problems with the exchange.

"One has to wonder how someone so critical to addressing numerous technical problems is free to take exotic vacations at this time," Craig said. "One does not abandon their post during a crisis, and this is unacceptable."

O'Malley's pledge to reshape the exchange and some of its leadership moves occurred while Pearce was in the Caribbean.

"That's pretty bad timing," said Donald Norris, professor of public policy at the University of Maryland, Baltimore County. "If you are responsible for something that is failing, you don't bail out on it until you fix it."

Earlier this year, in describing her role in implementing the Affordable Care Act, Pearce said, "It's not very often you get a chance to change history." She said that enrolling thousands of the state's 800,000 uninsured residents for coverage starting in 2014 was the final step in implementing President Obama's signature legislation: "We've built the present, wrapped it, and now we're trying to put the bow on it."

Sharfstein declined to discuss Pearce's vacation and whether he knew about it in advance. Department of Health and Mental Hygiene spokesman Dori Henry said that Pearce's trip included three days state government was closed for the Thanksgiving holiday.

"She's basically the CEO of a that multimillion-dollar corporation," said House Minority Leader Nic Kipke, an Anne Arundel County Republican. "I suspect in the private sector when there's a lot on the line, that a CEO wouldn't disappear during a major crisis."

Pearce answers to an executive board that was appointed by O'Malley and is chaired by Sharfstein, who told lawmakers on the Senate Finance Committee last week that he could not predict when the exchange would be free of glitches.

Sen. John Astle, an Annapolis Democrat and vice chair of the committee, said that taking a vacation over the Thanksgiving holiday was not a big deal, especially when other officials could speak on her behalf. "I didn't even miss her, to tell you the truth," he said.

But others were surprised to learn a key player was not around.

Republican Sen. David Brinkley, the minority leader, said, "As long as this thing is dysfunctional, I think there's a reasonable expectation from the taxpayers that the people overseeing it would be working as hard as possible to fix it."